leds: LED driver for National Semiconductor LP3944 Funlight Chip
LEDs driver for National Semiconductor LP3944 Funlight Chip
http://www.national.com/pf/LP/LP3944.html
This helper chip can drive up to 8 leds, with two programmable DIM
modes; it could even be used as a gpio expander but this driver assumes
it is used as a led controller.
The DIM modes are used to set _blink_ patterns for leds, the pattern is
specified supplying two parameters:
- period: from 0s to 1.6s
- duty cycle: percentage of the period the led is on, from 0 to 100
LP3944 can be found on Motorola A910 smartphone, where it drives the rgb
leds, the camera flash light and the displays backlights.
Signed-off-by: Antonio Ospite <ospite@studenti.unina.it>
Signed-off-by: Richard Purdie <rpurdie@linux.intel.com>
diff --git a/Documentation/leds-lp3944.txt b/Documentation/leds-lp3944.txt
new file mode 100644
index 0000000..c6eda18
--- /dev/null
+++ b/Documentation/leds-lp3944.txt
@@ -0,0 +1,50 @@
+Kernel driver lp3944
+====================
+
+ * National Semiconductor LP3944 Fun-light Chip
+ Prefix: 'lp3944'
+ Addresses scanned: None (see the Notes section below)
+ Datasheet: Publicly available at the National Semiconductor website
+ http://www.national.com/pf/LP/LP3944.html
+
+Authors:
+ Antonio Ospite <ospite@studenti.unina.it>
+
+
+Description
+-----------
+The LP3944 is a helper chip that can drive up to 8 leds, with two programmable
+DIM modes; it could even be used as a gpio expander but this driver assumes it
+is used as a led controller.
+
+The DIM modes are used to set _blink_ patterns for leds, the pattern is
+specified supplying two parameters:
+ - period: from 0s to 1.6s
+ - duty cycle: percentage of the period the led is on, from 0 to 100
+
+Setting a led in DIM0 or DIM1 mode makes it blink according to the pattern.
+See the datasheet for details.
+
+LP3944 can be found on Motorola A910 smartphone, where it drives the rgb
+leds, the camera flash light and the lcds power.
+
+
+Notes
+-----
+The chip is used mainly in embedded contexts, so this driver expects it is
+registered using the i2c_board_info mechanism.
+
+To register the chip at address 0x60 on adapter 0, set the platform data
+according to include/linux/leds-lp3944.h, set the i2c board info:
+
+ static struct i2c_board_info __initdata a910_i2c_board_info[] = {
+ {
+ I2C_BOARD_INFO("lp3944", 0x60),
+ .platform_data = &a910_lp3944_leds,
+ },
+ };
+
+and register it in the platform init function
+
+ i2c_register_board_info(0, a910_i2c_board_info,
+ ARRAY_SIZE(a910_i2c_board_info));
